N-hydrocarbylphosphoric triamides and N-hydrocarbylthiophosphoric triamides are known to be effective urease inhibitors for use with urea-based fertilizer compositions. See, for example, U.S. Pat. No. 4,530,714 to J. F. Kole, et al.
Known procedures for preparing such triamides involve operations in which N-hydrocarbylaminophosphoryl dichloride (also known as N-hydrocarbylphosphoramidic dichloride) or N-hydrocarbylaminothiophosphoryl dichloride (also known as N-hydrocarbylthiophosphoramidic dichloride) is formed in a first reaction, recovered, and often purified. In a second reaction, the N-hydrocarbylaminophosphoryl dichloride or N-hydrocarbylaminothiophosphoryl dichloride is reacted with ammonia to produce a slurry from which co-product ammonium chloride is separated by filtration. See for example, U.S. Pat. No. 4,530,714.
Filtration of the co-product ammonium chloride from the reaction product mixture can be a difficult and time-consuming operation, especially if the process is being conducted on a large scale in commercial-type production facilities. A desirable contribution to the art would be a process wherein the filtration of co-product ammonium chloride formed in the production of N-hydrocarbylphosphoric triamides or of N-hydrocarbylthiophosphoric triamides can be eliminated. An additional desirable contribution would be to enable formation of a useful liquid co-product mixture containing the ammonium chloride formed in the process.
The NH.sub.4 Cl and NH.sub.3 binary system has been discussed in the literature. See, for example, Hideki Yamamoto, Seiji Sanga, and Junji Tokunaga, The Canadian Journal of Chemical Engineering, Vol. 66, February 1988, pp 127-130 ("Measurement of Heat of Mixing for Ammonium Chloride+Ammonia at 25.degree. C."); James Kendall and J. G. Davidson, J. Am. Chem. Soc. 1920, Vol. 42, pp 1141-1145 ("Addition Compounds of Ammonia with the Ammonium Halides"); and Sueyoshi Abe, Kyozo Watanabe, and Tatsusaburo Hara, J. Soc. Chem. Ind. Japan, 1935, Vol, 38, pp 1402-1406 ("Solubilities and Vapor Pressures of NH.sub.4 Cl+NH.sub.3 System").